Recently, the MO-CVD method has gained attention as a method for producing a semiconductor laser element by crystal growth. The MO-CVD method is a method whereby crystal growth is executed by utilizing a kind of thermal decomposition with the metal organic of a group III element such as trimethyl gallium and trimethyl aluminum, and a material that includes a group V element, such as arsine (AsH.sub.3) gas, as the main raw material. This method is superior in view of the uniformity of film thickness and the quality of grown film, and furthermore in view of capability of executing a crystal growth on a large-sized wafer. Therefore, this method is advantageous as a mass-production method of laser crystals, and it is expected that the conventional liquid phase growth technique should be replaced thereby. However, even in this MO-CVD method, there is a disadvantage that it is difficult to grow the crystallization so as to embed a groove. This unfavourably restricts laser structures to which this MO-CVD method can be applied. For example, this method is not applicable to the production of a refractive index guide type semiconductor laser where a GaAs substrate is provided with a groove, a double hetero-structure is laminated embedding the groove, and an effective light guide is constructed in such a manner that the light is absorbed by the portions of the substrate located at the both sides of the groove, a configuration that is realized by a liquid phase growth method. The MO-CVD method is mainly utilized in a so-called gain guide structure laser element where the light is guided by the gain distribution in the horizontal direction, without any structure as a refractive index guide in the horizontal direction of the active layer.
However, such a gain guide type laser element has disadvantages in that it requires a large operational current and a large astigmatism relative to the refractive index guide type laser, and the latter type laser is more appropriate for practical use in view of typical life time of the device.
Another prior art semiconductor laser is reported in an article "Visible GaAlAs V-channeled substrate inner stripe laser with stabilized mode using p-GaAs substrate" by S. Yamamoto et al, Applied Physics Letters, vol. 40, p 372 to 374. The semiconductor laser of this article has an internal current confinement structure similar to that of the present invention.
Another prior art semiconductor laser is reported in "Single-longitudinal-mode CW room-temperature Ga.sub.1-x Al.sub.x As-GaAs channel-guide lasers grown by metal organic chemical vapour deposition", by R. D. Dupuis and P. D. Dapkus, Applied Physics Letters, vol. 33, p 724 to 726. The semiconductor laser of this article has a groove or a channel at the lower portion of the active layer, and the active layer has a curved configuration similar to that of the present invention.